Overdrive system



Aug. 3, 1954 H. F. HEISLER' v ovERnRIVE SYSTEM 6 Sheets-Sheet 2 FiledJan. 2v, 1951 I'II' Aug. 3, 1954 H. F. HELSLER 2,685,210 ovERDRIVESYSTEM I Fil'edJan. 27, 1951 I l v 6 Sheets-Sheet 3 A1193, 1954 I H. F.HElsLER 2,685,210v

OYERDRIVE' SYSTEM Filed Jan. 27,'1951 A ZAw/elnor.' Jarry Fu/ezlsler .Bwww Aug` 3, 1954 H. F. HE|sLER 2,685,210

i OVERDRIVE SYSTEM Filed Jan. 27, 1951 6 Sheets-Sheet 5 2 il J 12 132\\3 Aug-.3, 1954 H. F. HElsLER y2,685,210

ovERnRIvE SYSTEM Filed Jan. 27; 1951 6 Sheets-Sheet 6 l N V EN TOR.

Patented Aug. 3, 1954 UNITED STATE ATENT OFFICE Claims.

This particular application is a continuationin-part application of mypending application, Serial No. 150,852, on an Overdrive System, filedon March 21, 1950.

This invention relates to an overdrive system, and more particularly toan overdrive system which is easily adapted to existing transmissions oftractors and the like. The range of power speeds of farm tractors isvery limited and the top speed of the usual power speed range isrelatively low. For example, a typical tractor may have four powerspeeds ranging from 21/2 miles per hour to about 51/2 miles per hour.Tractors are also often equipped with a fth speed of about 18 miles perhour which is attainable only when there is very little or no load onthe tractor, and which speed is attained by connecting the drive shaftdirectly to the supply of power, thereby by-passing the countershaft.The tractors power speeds are designed low because the loads carried orhauled by tractors are usually very large and greater pulling power ortorque is developed at lower speeds.

However, there are many occasions when the tractor is moving betweenjobs when it is unloaded or partially unloaded and higher power speedsare desirable. When those occasions arise, the tractor is unable to meetthe demand for higher speeds, because of the low gear ratios which areavailable in the transmission. The high direct drive speed is oftenimpractical if the tractor is partially loaded or if the terrain overwhich the tractor is moving is rough. Thus it is desirable to provideintermediate power speeds having values between the highest of theexisting power speeds and the high direct drive speed. While it is truethat the entire transmission could be changed to give these higher powerspeeds, the high torque, lower power speeds would be lost in such anarrangement, which would be undesirable.

In adapting an overdrive system to an existing transmission, it isdesirable to retain as much as possible of the existing transmission. Ifpossible, it is desirable to integrate the overdrive system with theexisting shifting arrangement for the transmission. The adaptation of anoverdrive to an existing transmission without losing the original speedsof the transmission requires the use of additional shiftable members l'and means whereby the shiftable members are actuated. The proper use ofsuch additional shiftable members is predicated, in some degree, upon ameans for positioning and retaining the shiftable members inpredetermined positions.

Thus, one of the objects of this invention is to provide a noveloverdrive system for tractors which provides a range of higher speedswithout sacricing the existing range of high torque lower speeds.

Another object of this invention is to provide an overdrive system foruse within the transmission housing of the vehicle, which may be easilyadapted to the existing transmission system.

A further object of this invention is to provide an overdrive systemwhich is designed to be easily tted into the existing transmissionhousing for a motor vehicle.

A still further object of this invention is to provide a novel overdrivesystem, which converts an existing four speed transmission into an eightspeed transmission, or an existing five speed transmission into a ninespeed transmission.

Another object of this invention is toprovide a novel ball poppet meansfor positioning coaxial members, which are shiftable axiallytherebetween, with respect to each other in a plurality of predeterminedpositions.

Still another object of this invention is to provide a novel shiftingmeans which consists of simple and inexpensive linkages for use with thenovel overdrive system, which shifting means is easily adapted to theexisting transmission structure.

And still a further object of this invention is to provide a novelsupport means within the transmission housing for performing the dualfunction of supplying a journal for a rock shaft of the shifting meansand for supporting a guide collar for the shifting lingers.

Further objects and advantages of this invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize this invention will be pointed out with particularity inthe claims annexed to and forming part of this specication.

A preferred embodiment of the invention is shown in the accompanyingdrawing, in which- Figure 1 is a cross sectional side View of the driveshaft and the countershaft of a typical transmission for a tractor,which have been modied to include elements of my invention, and showsthe shiftable clutch collar, mounted on the countershaft, shifted intothe overdrive speed position.

Figure 2 is a top plan view, partly in cross section, of thecountershaft and reverse gear shaft of a typical transmission for atractor, which have been modified to include elements of my 3 invention,which view is taken on line 2 2 of Figure 1.

Figure 3 is an end view, partly in cross section, of the transmissionhousing and the modified shafts and gears mounted therein, and is takenon line 3-3 of Figure l.

Figure 4 is a cross section View of one of the rock shafts in theoverdrive shifting linkage and is taken on line 4-4 of Figure 3.

Figure 5 is an end view, partly in cross section, of the modified driveshaft and countershaft, showing the ball poppet means in more detail,and is taken on line 5 5 of Figure 1.

Figure 6 is another cross sectional end view of the shafts and gearswithin the transmission housing, and is taken on line E-E of Figure l.

Figure 7 is a top plan View, partly in cross section and partly inelevation, with portions of the transmission housing broken away, of aportion of the overdrive shifting linkage, and is taken on line 1-1 ofFigure 3.

Figure 8 is a side view of the part of the overdrive shifting linkageshown in Figure r1, and also shows the actuating rod for the shiftinglinkage.

Figure 9 is a cross sectional view of the shiftable clutch collarmounted on the countershaft, showing the clutch collar shifted into theregular speed position.

Figure 10 is a cross sectional view of the clutch collar andcountershaft, and is taken on line Ill-l 0 of Figure 9.

Figure 11 shows substantially the major parts, other than the shiftinglinkage, that are supplied for adapting the overdrive system to theexisting transmission. The view is similar to that in Figure 2, with theaddition of the two gears that are supplied for the drive shaft. Theselatter two gears are shown in Figure 11, rotated out of verticalposition but positioned axially substantially as they would be in thetransmission housing. The parts in Figure 11 outlined in dotdash lineare parts that are similar to previous existing parts in thetransmission but which are, nevertheless, replaced.

Figure 12 is similar to the left-hand half of Figure 1 and shows amodified form of my invention, wherein the relative positions of thepower drive gears are reversed, and'wherein a modified arrangement foraxially positioning the driven gears is provided.

Figure 13 is similar to the left-hand half of Figure l and shows anothermodified form of my invention, wherein the second power drive gear ismounted on the extension shaft and the relative positions of the powerdrive gears are reversed, and wherein a modified arrangement for axiallypositioning the driven gears is provided.

For the purposes of this description of my invention, I have elected todescribed the modifications on a typical five speed tractor. Thestandard arrangement of elements in the tractors transmission housingincludes a drive shaft, a countershaft and a reverse gear shaft. Thecountershaft is journalled in bearings in a pair of opposite walls ofthe transmission housing. The reverse gear shaft is shorter than thedrive shaft or countershaft and is supported at one point in one wall ofthe transmission housing and supported at another point by a standardlocated in the transmission shifting chamber, substantially inmid-length thereof.

The drive shaft is journalled at one point in a bearing mounted in awall of the transmission housing and extends into the transmissionshifting chamber. The other support for the drive shaft is a bearing forthe extended end of the drive shaft, which bearing is journalled withina concentric recess of the power drive gear. The power drive gear itselfhas an extension shaft formed integrally therewith and journalled inbea-rings in another wall of the transmission housing. Effectively, thedrive shaft is supported by bearings in opposite walls of thetransmission housing through the bearing joint in the recess of thepower drive gear.

'This power drive gear which is coupled to the source of power is inmesh with a single countergear splined to the countershaft, whereby thecountershaft is rotated when the power drive gear rotates. The bearingwhich is at the end of the drive shaft, and is journalled in the powerdrive gear recess, permits overriding of the power drive gear on thedrive shaft.

Also non-shiftably splined to the countershaft are a pair of spaceddouble gears, each gear being of a different diameter and adapted tomesh with other gears on the drive shaft, whereby Said drive shaft isrotated at different speeds, One each of the two pairs of double gearscorrespond to speeds referred to as first, second, third, and fourth.The gear that corresponds to second speed is in mesh with a first gearrotatably mounted on the reverse gear shaft.

The reverse gear shaft is xedly mounted within the transmission housing.The rst gear on the reverse gear shaft is connected by means of acollar, rotatably mounted on the reverse gear shaft, to a second gear.The nrst and second gears and the collar rotate as a unit.

On the drive shaft are two single and one double shiftable gears. Thesegears are splined to the drive shaft, whereby the rotation of any one ofthe gears will result in the rotation of the drive shaft. All the gearsare adapted to be shifted in opposite directions along the drive shaft.The rst single gear is adapted to engage the gear on the countershaftcorresponding to first when shifted in one direction, and to engage thesecond gear on the reverse gear shaft when shifted in the oppositedirection. The engagement with the second gear on the reverse shaftresults in rotation of the drive shaft in the reverse direction.

The double gear on the drive shaft is positioned between the spaced pairof double gears on the countershaft. When the double gear is shifted inone direction, one of its gears engages the gear on the countershaftcorresponding to second, and when shifted in the opposite direction, theother gear of the double gear meshes with the countershaft gearcorresponding to third. Similarly, the second single gear on the driveshaft when shifted in one direction engages the countershaft gearcorresponding to fourth.

This second single gear on the drive shaft is also provided with aninternally splined recess whereby when it is shifted, in the oppositedirection to that wherein the fourth speed gear was engaged, theinternal splines engage the teeth of the power drive gear rotatablyjournalled at the end of the drive shaft, whereby a fifth speed isprovided. The internal splines on the second single drive shaft gearengage only a portion of the power drive gear edge. This is provided forby reducing the diameter of the power drive gear over the portion to beengaged. Then the portion of the power drive gear that is not reduced indiameter engages the second single drive shaft gear at a bearinginterface and limits the extent of shift of the second single gear. Thisis desirable to preventI the second single driveshaft gear from beingshifted to an interfering position with the single countergear on thecountershaft.

As is well known in the art, when any shiftable gear is in mesh, all theother shiftable gears are disengaged.

Referring now to the modified form which incorporates the elements of myinvention and, as shown in the figures, there is shown in Figure '1 atransmission housing, generally indicated at I0, enclosing atransmission shifting chamber I I. A power drive gear I2 is part of adouble gear I4 integrally formed with extension shaft I6. The extensionshaft is journalled by bearing I8 in wall of transmission housing I6.The power drive gear I2 has a recess 22 therein adapted to receivesealed bearing 24.

A drive shaft generally indicated at 26 is journalled at a regionintermediate its ends by means of bearing 28 in wall 30 of transmissionhousing I0. Other support for drive shaft 26 is located at the extendedend thereof andcomprises bearing 24 which is secured to drive shaft 26by means of bolt 32. Thus, the drive shaft 26 is effectively supportedby bearings I8 and 28 in walls 20 and 30 of transmission housing I0through the bearing joint comprising bearing 24 in recess 22 of powerdrive gear I2.

The drive shaft 26extends through wall `36 of the transmission housinginto chamber 34 within the transmission housing. Mounted on the end ofthe shaft 26 which extends into chamber 34 is a pinion gear 36 which isthe power takeoe for the wheels of the tractor.

A countershaft 38 is shown rotatably mounted in bearings 40 and 42 whichare respectively positioned in walls 26 and 30 of transmission housingI0. One end of countershaft 38 is provided with an attachment 44 whichmay be connected to a hydraulic system pump (not shown) so as to actuatethe hydraulic system of the tractor. The other end of countershaft 38 issplined as at 46 so as to provide means for driving the auxiliarytake-off which powers the attachments to the tractors.

As seen more clearly in Figures 2 and 3, a new reverse gear shaft 48 isxedly mounted in supports 50 and 52 within the transmission housing.Support 50 is integral with wall 30 of transmission housing and support52 projects into the transmission housing chamber about midway betweenwalls 20 and 36 of the transmission housing. A pin 54 extends throughsupport 52 and through reverse gear shaft 48, thereby fixing shaft 48 inposition in supports 50 and 52. The new reverse gear shaft 48 extendsbeyond support 52 as at 49, to provide a support for a bracket, as willbe hereinafter described.

Referring back to the drive shaft and to the power drive gear, as shownin Figure 1, the power drive gear I2 is reduced in diameter over aportion of the gear edge thereof, as indicated at 56. The drive shaft 26is provided with two single and one double shiftable gears. These gearsare splined to the drive shaft 26 and are rotatable therewith and areadapted to be shifted in either direction along the drive shaft 26. Therst shiftable single gear 58 is adapted to engage the gear on thecountershaft corresponding to first speed when shifted in one directionand to engage the reverse speed gear when shifted in the oppositedirection. The double shiftable gear 60 has two gear faces 62 and 64thereon. Gear 62 is adapted to engage the second speed gear on thecountershaft when the double gear 60 is shifted in one di# rection, andgear 64 is adapted to engage the third speed gear mounted on thecountershaft when the double gear 66 is shifted in the oppositedirection. Ihe second single shiftable gear 66 is adapted to engage thefourth speed gear when it is shifted in one direction. Each of theshiftable gears 58, 60, and 66 is provided with grooves 59 thereinadapted to receive means (not shown) for shifting said gears. The meansfor shifting these gears, provided in the original transmission, areretained herein and are well known in the art.

The single gear 66 in the original iive speed setup was provided withinternal splines to engage the reduced portion 56 of the gear edge ofpower drive gear I2. In the modified form herein, a portion of thespline length of shaft 26 has been reduced in diameter to eliminate thesplines and to provide a bearing surface as at 68. Mounted on thereduced diameter portion 68 of shaft 26 is a ball bearing 10. A secondpower drive gear 'I2 is mounted on the bearing 'I0 and, therefore, isrotatably mounted on shaft 26. This second power drive gear 'I2 isprovided with an internally splined recess 'I4 adapted to engage thereduced diameter portion 56 of the gear edge of power drive gear I2. Asnap ring I6 acts to keep the two power drive gears constantly in mesh,so that they rotate as a unit. The shoulder 'I8 in shaft 26 acts to keepthe bearing 'I0 axially restrained from movement along the shaft. Thegreater diameter portion of the gear edge of power drive gear I2 buttsagainst the face of the second power drive gear 'I2 at the interface 80,thereby restraining the gear 'I2 from axial movement in the oppositedirection.

The second power drive gear 'I2 has a reduced diameter portion on itsgear edge 82, as shown in Figure 1. The shiftable single gear 66 isprovided with a splined internal recess 84 which is adapted to engagethe second power drive gear 'I2 over the reduced diameter portion 82 ofits gear edge, when the shiftable single gear 66 is shifted to the left,as seen in Figure 1. The larger diameter portion of the gear edge ofpower drive gear I2 provides a bearing interface 86 against which theshiftable single gear 66 butts when it is shifted to the left, asdescribed above. This bearing interface 86 provides a stop for limitingthe motion of gear 66 in the direction to the left, as shown in Figurel.

Referring next to the countershaft 38, a first and second driven gear isshown in mesh with the first and second power drive gears. A firstdriven gear 68 is shown in mesh with power drive gear I2. This firstdriven gear 88 is rotatably supported on bearings 96 which are mountedon a reduced diameter section 92 of countershaft 38. A second drivengear 94 is rotatably mounted with respect to countershaft 38 and is inmesh with the second power drive gear 12.

Splined to the countershaft 38 is a clutch co1- lar 86 which isrotatable with countershaft 38 and is shiftable in an axial directionthereon. A bearing 98 mounted on the outer periphery of clutch collar 96is adapted to receive and support the rotatably mounted gear 04. Alsosplined to countershaft 38 are a pair of double gears |00 and |02. Snaprings |64 are adapted to engage the faces of double gears |06 and |62 toprevent their axial movement along the countershaft 38. Gear |06 ofdouble gear |00 corresponds to a first speed and is adapted to beengaged by rst shiftable single gear 58 mounted on drive shaft 26. Gear|08 of double gear |00 corresponds to the second speed gear and isadapted to receive gear 62 of shiftable double gear 6a mounted on driveshaft 26. Gear of double gear |02 corresponds to thirdspeed and isadapted to receive gear 64 of shiftable double. gear 60 which is mountedon drive shaft 26. Gear ||2 of double gear |02 corresponds to fourthspeed and is adapted to receive gear face 61 of the second shiftablesingle gear 66 mounted on drive shaft 26.

As seen more clearly in Figures 2 and 3, a pair of gears ||4 and ||6joined together by a collar |8 are rotatably mounted on reverse gearshaft 48. Gear ||4 is in mesh with the second speed `gear oncountershaft 38 which is gear |88 of double gear |00. The gear ||6 isadapted to be engaged by the shiftable single gear 58 which is mountedon drive shaft 26.

Thus far the gears and their relationship to each other have beendescribed. The manner of driving the countershaft through the powerdrive gears will now be disclosed. As set forth above, a clutch collar85 is splined to shaft 38 and is shiftable in an axial directionthereon. One end of clutch collar 96 has formed thereon a gear |20. Thefirst driven gear 88 has formed therein an internally splined recess |22which is adapted to receive and engage the teeth of gear |28 when theclutch collar 86 is shifted to the left when viewed as in Figure l, andwhich position is shown in Figure 9. The second driven gear 94 has aninternally splined recess |24 which is adapted to receive and engage theteeth of gear |28 when the clutch collar 96 is shifted to the right,which is the position shown in Figure l. The first driven gear 88 isalso provided with an enlarged recess |26 which is of greater diameterthan the gear |20 and which is positioned between the splined recesses|22 and |24. When gear |28 is positioned in recess |26, both the irstdriven gear 88 and the second drive gear 94 are disengaged from clutchcollar 96.

A ball poppet means for axially positioning the clutch collar 96 withrespect to the drive shaft 38 is also provided and is best shown inFigures l and 5. Referring to Figure 5, a plurality of radiallyextending cylindrical bores |28 are provided in countershaft 38. Thesebores |28 are located in alternate crotches between the splines. Theball poppet means further comprises a compression spring |30 positionedin each bore |28, and a steel ball |32 mounted in each bore |28 adjacentthe mouth thereof. These balls |32 are in engagement with the spring |30in the bore |28, and are resiliently biased outwardly from bore |28.

The clutch collar 98 is provided with a plurality of arcuate grooves |34located in the faces of the splines of the clutch collar 96. Thesearcuate grooves lie in planes perpendicular to the longitudinal axis ofthe clutch collar 36 and the countershaft 38, and are adapted to receivethe resiliently biased balls |32, whereby resistance to axialdisplacement by the clutch collar 86 and the countershaft 38 isobtained. As shown in Figure l, these arcuate grooves |34 are providedin three planes to provide for the three positions of the clutch collar;the first position, as shown in Figure l, being with the gear |20 inmesh with splined recess |24, the second position being with gear |20positioned in recess |26, and the third position being with gear |28 inmesh with splined recess |22.

The mechanism for sluiting the clutch collar 96 includes a bracketgenerally indicated at |36, best shown in Figures 2, 3 and l1. Thebracket |36 has a cap portion |38 which is split so that the cap |38 maybe adjustably clamped on the extended end 49 of reverse gear shaft 48,by means of bolt |40. The bracket |36 has extending from the cap portion|38 an arm |42 which has drilled therein a vertical bore |44 adapted toreceive a rotatable member. Also extending from arm |42 is a collar |46which is coaxially positioned around the clutch collar 96. The collar|46 is spaced from the surface of clutch collar 96, so as to provideclearance between the two coaxial members.

A pair of control arms |48 and |50 are joined together by a shaft |5|,which is rockably mounted within vertical bore |44 in arm |42. The arms|48 and |50 extend on opposite sides of the clutch collar 96 and collar|46, A finger |52 is mounted at the extended end of each arm |48 and|50. The ngers |52 are oppositely facing and are positioned in avertical plane which passes through the axis of countershaft 38, clutchcollar 96, and collar |46. The clutch collar 96 is provided with acircumferential channel or groove |54 which is adapted to receive thepins |52. Arcuate bearing strips |56 are positioned in thecircumferential groove |54 and receive the extended tips of fingers |52in holes |58 therein, provided for that purpose. The collar |46 isprovided with elongated slots |60 through which the fingers |52 pass toenter into the circumferential groove |54 in clutch collar 86. When theshaft |5|., together with arms |48 and |58 are pivoted, the ngers |52are swung in substantially an axial direction relative to thecountershaft 38. This axial motion of ngers |52 is transmitted throughbearing |56, through the walls of groove |54, to clutch collar 86,thereby effectuating a shifting of the clutch collar 96.

In order to pivot the arms |48 and |58 together with shaft |5| withinbore |44, it is necessary to provide a control linkage, which is mostclearly shown in Figures 2, 3, 7 and 8. 'I'he arm |48 is connected by alink |82 to a toggle member |64 mounted within the transmission shiftingchamber enclosed within transmission housing |0. The toggle member |64is a'ixed to a rock shaft |66, which is mounted in the wall of overdrivehousing l0, as shown in Figures 2, 3 and 4. As shown clearly in Figure4, rock shaft |66 passes through an axial bore |68 of an insert |18positioned in a hole |1| in the wall of transmission housing i8. Thehole |1| is formed by reaming out a tapped oil plug hole in housing i8.A pair of grease seals |12 are provided to prevent the leakage of greaseor oil between insert |10 and the wall of transmission housing I8. Apacking |14 is provided between rock shaft |66 and insert |58 to preventleakage of oil past the face between those two members. A cap |16 isprovided for keeping the packing |14 in position and is threaded to theextended end of insert |18, whereby the entire insert assembly may beclamped together by tightening up on cap |16. A toggle member |18 issecured by means of set screw |80 to the end of rock shaft |66, whichextends outside of the transmission housing I8. The toggle member |18 isactuated by a link |82 which in turn is reciprocated by a toggle member|84 welded to a control rod |86. The control rod |86 is supported by asupport bracket |88. The control rod |86 passes through a hole |98 insupport bracket |88 and is prevented from further passage therethroughin one direction by the toggle member |84 which is welded to the controlrod |86. The control rod |86 is prevented from movement through the hole|30 in the opposite direction by means of cotter pin |32.

It can be seen that by rotating the control arm |86, the linkage carriesthe motion through the rock shaft |68 through the linkages to thecontrol arms |48. 'I'he arms |48 and |50 are swung through an arc, bymeans of rock shaft I! which is pivoted within bore |44, to effectuateshifting of the clutch collar 96.

A means for axially positioning the driven. gears 88 and 94 with respectto the countershaft 38 is also provided, as shown in Figurey 1. A ring|94 is positioned between bearing 98 and shoulder |86 on countershaft38. This ring |84 positions the bearing 90 with respect to motion to theleft. A snap ring |88 is mounted in an inner recess in first driven gear88 and engages the bearing 86. The rst driven gear 88 and second drivengear 94 have a bearing interface 200 therebetween.. In order to restrictthe mot.. on of second driven gear 94 in the direction to the right, asseen in Fi.,- ure 1, a pair of spacer rings 202 and 264 are provided onopposite sides of collar I 46, with the spacer ring 204 being insertedin a recess in double gear |02, which gear |62 is fixed axially relativeto countershaft 38 in the manner described above. It can be seen thatthe ring |94 and shoulder |96 cooperating with snap ring |88, spacerrings 202 and 204, collar |46 and double gear |82 together clamp thedriven gears 88 and 84 in substantially non-movable positions axially,while driven gears 88 and 94 remain rotatably mounted with respect tocountershaft 38.

In the form of the invention shown in Figure i, the extension shaft I6is provided with a double gear I4. One of the gears I2 of double gear I4constitutes the first power drive gear. The second power drive gear 'I2is splined to the first power drive gear, but is rotatably mounted on areduced portion of the drive shaft 255. A second gear I3 of the doublegear I4, integral with the extension shaft I6, retains its previousfunction of driving some member which is not a necessary part of thisinvention.

In the form of the invention shown in Figure 12, this second gear I3 ofthe double gear I4 is used as the second power drive gear. .Also shownin ligure'lI is another arrangement of the use of spacers and snap ringsto keep the driven gears in fixed axial position with respect to thedrive gears.

Referring now more specifically to Figure 12, the extension shaft I6 isjournalled in the wall 20 by means of bearing I8. As described above,the extended end of drive shaft 26 is supported `by means of bearing 24within recess 22 at the end of extension shaft I8. The first power drivegear I2 is reduced in diameter over a portion of the gear edge thereofas indicated at 56. This reduced portion of the rst power drive gear I2is 'adapted to mesh with internal dental elements 220 formed in thesecond single shiftable gear 66.

The gear 66, with the internal dental elements 220, is the same as thatsupplied in the unmodied transmission of the manufacturer. It is aprimary purpose in this modified form to use as many of the originalparts as possible to obtain the same end results.

The first power drive gear I2 is in mesh with a driven gear 222 and thesecond power drive gear I3 is in mesh with a second driven gear 224.These driven gears 222 and 224 are mounted with respect to thecountershaft 38 in the same manner as the respective gears 94 and 88shown in Figure 1, except for minor mechanical variations.

It is pointed out, however, that gear 94 in Figure 1 was in mesh withthe second power drive gear and was rotatably mounted on the clutchcollar 86, while gear 222 is in mesh with the rst power drive gear andis rotatably mounted on the clutch Collar 9S.

To eliminate any possible axial movement of the driven gears withrespect to the countershaft 38, an arrangement of spacers and snap ringsis provided. The gear 224 is shown rotatably mounted on countershaft 38by means of bearings 226 and 228. A snap ring 230 is mounted oncountershaft 38 and restrains spacer 232 which engages the lower race ofbearing 226. A spacer 234 is provided between the lower races ofbearings 226 and 228 and the lower race of bearing 228 butts against ashoulder 236 formed in countershaft 38. A snap ring 238 is positioned ina recess in gear 224 and engages the upper races of bearings 226 and22S. The bearings 226 and 228 are restrained from axial movement alongcountershaft 38 by means of the snap ring 230, the spacers 232 and 234,and the shoulder 236. The snap ring 238 restrains the gear 224 frommovement axially on the outer races of the bearings 226 and 228.

The gears 222 and 224 have a butting interface 240 therebetween. Thisprevents movement of the gear 222 axially to the left, as shown inFigure 12, on countershaft 38. The gear 222 is rotatably mounted onbearing 88 which is concentrically mounted on clutch collar 96. Toprevent any movement of the gear 222, axially to the right with respectto countershaft 38, there is provided a spacer 242, a collar |46, and asecond spacer 244.

As was described above, the double gear |02 is restrained from axialmovement on countershaft 38 by means of snap rings |04. The spacer 242also engages the bearing 98 and prevents movement thereof to the right.The spacer 244 is of a size sufficient to accommodate any space betweenthe collar I 46 and the recessed face of double gear |02.

In the form of my invention shown in Figure 13, the second power drivegear is also mounted on the extension shaft I6, but is separate from thesecond gear I3 of the double gear I4 so that the original use of thegear I3 may still be retained. It has also been found that the size ofthe second driven gear is somewhat restricted by the shape of thetransmission housing when the second driven gear is in mesh with thegear I3, as shown in Figure 12. This is because there are certain fairedsurfaces in the interior of the transmission housing which interferewith driven gears of larger diameter. But by moving the second drivengear further away from the Wall 20 of the transmission housing I8, thesefaired surfaces are avoided, permitting the use of larger gears.

It is, therefore, the purpose in this modification to provide a seconddriven gear which could be positioned further away from the wall 20 ofthe transmission housing I0, thereby permitting use of more desirablegear ratios. Accordingly, the extension shaft I6 is modified so thatonly the rst power drive gear I2 is integral therewith. A second powerdrive gear 300 is keyed to extension shaft I6 by means of key 302. Agear 304 corresponding to gear I3, as shown in Figures 1 and 12, is alsoprovided and it, too, is keyed by means of key 302 to extension shaftI6. This gear 384 performs the same function as gear I3. A first drivengear 306 is in mesh' with first power drive gear l2 and the seconddriven gear 308 is in mesh with second power drive gear 380.

The type of bearing support for the extension shaft I8 is more elaboratein Figure i3 than is shown in Figures 1 and 12, and includes a bearingcage 3H) which is bolted, by means of bolts 312, to the wall 20 of thetransmission housing l0. This bearing cage 3l8 has a pair of bearings3I4 and 3l6 mounted therein. I'he outer races of the bearings 3|4 and3l6 are restrained in the cage 3 I 8 by means of snap rings 3I8 and 320and by means of shoulders 322 and 324. A spacer 32S,

i concentric with extension shaft I6, is provided thereof. Similaraxially extending hub portions on driven gears 305 and 308 butt againsteach other to form an interface 338 which prevents engagement by thegear face of first driven gear 300 with hub portions of the first drivengear 383 during rotation thereof.

The axial positioning of the driven gears 303 and 308 to prevent axialmovement thereof with respect to the countershaft 38 includes a bearingcage 332 which fixes the bearing 40 with respect to the wall 20. Aspacer 334, concentric with countershaft 38, engages the inner race ofbearing 40 and the hub portion 338 of second driven gear 308. The hubportion 336 is restrained from moving to the left by spacer 334, and isrestrained from moving to the right by shoulder 338 in countershaft 38.A sleeve bearing 340 is provided for the second driven gear 308 and hasa stepped portion which engages shoulder 342 in countershaft 38. Thebearing 340 is restrained from movement to the left by spacer 334 and bymovement to the right by shoulder 342.

The first driven gear 386 is restrained from axial movement to the leftwith respect to countershaft 38 by the butting interface 330. Asemicircular ring 344 which is integral with bracket 38 engages the faceof gear 308 to restrict movement of gear 306 toward the right. Thissemicircular ring 344 is positioned concentric with the hub portion 343of gear 305. In the modified form shown in Figure 13, the collar M6shown in Figures 1 and l2 has been eliminated as the semicircular ring344 performs the same function of restraining movement of the drivengear axially to the right. The bracket |36 is mounted on the extendedend 49 of reverse gear shaft 48, as described hereinabove.

Operation In the operation of the transmission and overdrive, the firstand second power drive gears are always in mesh and rotate as a unit.The first driven gear 88 and second driven gear 94 are in meshrespectively with first power drive gear I2 and second power drive gear'i2 and hence are always rotated. When the clutch collar 96 is in theposition shown in Figure l, the first driven gear 88 is not rotating asfast as is the second driven gear 94. In the position shown in Figure 1,the second driven gear 04 is splined through clutch collar 96 tocountershaft 38, and the countershaft rotates with second driven gear94. At that time the first driven gear 88 is underrunning thecountershaft 38. To provide the various speeds for the tractor orvehicle, the transmission gears 58, 30 and 66 are shifted as before andprovide for different speeds.

When the clutch collar 98 is in the position shown in Figure 9, then thefirst driven gear 88 is splined in driving connection to thecountershaft 38 and the second driven gear 94 is overrunning withrespect to the countershaft 38. The bearing surface 98 between theclutch collar 98 and the second driven gear 94 provides for ease ofrotation. When in this position with the first driven gear in drivingconnection with the countershaft 38, there are still four more speedsavailable by shifting the gears 58, 80 and 86, into engagement with thegears mounted on and rotating with countershaft 38.

When the clutch collar is positioned so that gear 120 is within therecess |26, then neither the first driven gear nor second driven gearare in driving engagement with the countershaft 38 and hencecountershaft 38 does not rotate. At that point, only one speed isavailable for the wheels of the tractor and that is obtained by shiftinggear 88 in the direction where the internal splines 84 in gear 88 mayengage the recessed gear edge 82 of second power drive gear 12. In fact,even if the clutch collar 96 is in engagement with either of the twodriven gears 88 or 94, this speed resulting from the engagement ofrecessed gear edge 32 with internal splines 84 of gear 35 is alwaysavailable.

Thus, it can be seen that I have provided a novel overdrive system for amotor vehicle, which overdrive system may be easily fitted into theexisting transmission housing and adapted to the existing transmissionsystem therein, and which overdrive system preserves all the originalspeeds of the transmission besides providing a range of higher speeds,whereby for example an existing five speed transmission is convertedinto a nine speed transmission.

There have also been provided a simple and inexpensive shifting means, anovel support bracket for the shifting means adapted to be mountedwithin the transmission housing, and ball poppet means for positioningshiftable coaxial overdrive members with respect to each other in aplurality of predetermined positions.

While there has been shown and described a particular embodiment of thisinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made therein without departing from theinvention and, therefore, it is intended in the appended claims to coverall such changes and modications as fall within the tru-e spirit andscope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An overdrive gear system comprising first and second power drivegears rotating as a unit, a shaft, a first and a second driven gearsrotatably mounted coaxially with said shaft and respectively in meshwith said first and said second pbwer drive gears, means including anaxially shiftable clutch collar splined to said shaft for selectivelyconnecting said first or second driven gears in driving relation to saidshaft, one of said driven gears being rotatably mounted on said clutchcollar, and a sleeve surrounding said clutch collar and restrictingaxial motion of the driven gears with respect to said shaft, said sleeve13 having apertures therein through which shifting elements are adaptedto extend to engage the clutch collar for shifting said clutch collar.

2. An overdrive gear system comprising iirst and second power drivegears rotating as a unit, a shaft, a rst and a second driven gearsrotatably mounted coaxially with said shaft and respectively in meshwith said rst and said second power drive gears, means including anaxially shiftable clutch collar splined to said shaft for selectivelyconnecting said rst or second driven gears in driving relation to saidshaft, a transmission gear splined to said shaft and rotatabletherewith, and a sleeve surrounding said clutch collar acting as aspacer between said transmission gear and the driven gear rotatablymounted on the clutch collar for restricting axial motion of said drivengear with respect to said' shaft.

3. An overdrive gear system comprising first and second power drivegears rotating as a unit, a shaft, rst and second driven gears rotatablymounted coaxially with said shaft and respectively in mesh with saidfirst and second power drive gears, means including an axially shiftableclutch collar splined to said shaft for selectively connecting saidfirst or second driven gears in driving relation to said shaft, one ofsaid driven gears being rotatably mounted on said clutch collar, a stopmember concentric with said clutch collar engaging the driven gearrotatably mounted on said clutch collar to restrict axial movement ofsaid driven gear, a mounting bracket for said stop member adapted to nxsaid stop member axially in position, and means mounted on said bracketfor shifting said clutch collar.

4. An overdrive gear system comprising first and second power drivegears rotating as a unit, a shaft, rst and second driven gears rotatablymounted coaxially with said shaft and respectively in mesh with saidfirst and second power drive gears, means including` an axiallyshiftable clutch collar splined to said shaft for selectively connectingsaid rst or second driven gears in driving relation to said shaft, oneof said driven gears being rotatably mounted on said clutch collar,means including a stop member concentric with said clutch collar forengaging the driven gear rotatably mounted on said clutch collar torestrict axial movement of said driven gear, a mounting bracket for saidstop member adapted to x said stop member axially in position, said stopmember having elongated apertures therein, and means mounted on saidbracket for shifting said clutch collar, said means including shiftingelements extending through the apertures in said stop member andengaging said clutch collar.

5. An overdrive gear system as set forth in claim 3 wherein said stopmember is axially coextensive with only a portion of said clutch collar,and wherein said means for shifting said clutch collar includes shiftingelements spaced axially from said stop member and engaging said clutchcollar.

References Cited in the iile of this patent UNITED STATES PATENTS NumberName Date 2,115,390 Lasley Apr. 26, 1938 2,241,002 Peterson May 6, 19412,464,479 Avila Mar. 15, 1949

